Devices for administering drugs through the skin or mucosa have been described in many patents. These devices are usually of two types: matrix systems and liquid reservoir systems. Both systems are laminated composites that have, from basal to top, a peelable release liner, a pressure sensitive adhesive layer for attaching the device to the skin, a drug-containing layer, and a drug impermeable backing layer. In the matrix type system, the drug is dispersed within a solid or semi-solid carrier. In the reservoir type system, the drug, typically in liquid solution, is contained within a walled container, usually formed between the backing layer and a drug-permeable membrane layer.
A number of reservoir type systems have been described. U.S. Pat. No. 4,710,191 to Kwiatek et al. involves a reservoir type device that includes a peelable heat sealed release liner layer underlying the reservoir and the portion of the backing layer that extends beyond the reservoir. In a second embodiment, a microporous membrane is included between the backing layer and the reservoir.
U.S. Pat. No. 4,829,224 to Chang et al. describes a device with a reservoir that is defined by a backing layer and a drug-permeable membrane layer. A ring-shaped layer made of an adhesive is peripheral to the reservoir. A peelable liner layer underlies the membrane. A second peelable layer, the release liner, underlies the entire assembly. A first heat seal connects the backing layer and the membrane and surrounds the reservoir. A second heat seal concentric about the first heat seal connects the backing layer and the release liner. The second heat seal is broken when the release liner is removed. The device may include an inner liner that underlies the membrane and portions of the backing layer. This inner liner is removed following removal of the release liner so that the membrane is exposed.
U.S. Pat. No. 4,983,395 to Chang et al. relates to another device with a backing layer and a membrane layer that define a reservoir. A peelable inner liner underlies the reservoir and portions of the backing and membrane layers outside the periphery of the reservoir. An adhesive layer underlies the inner liner and remaining portions of the backing and membrane layers. A peelable release liner underlies the adhesive layer. A first heat seal connects the backing and membrane layers on the periphery of the reservoir. A second heat seal underlies the first heat seal and connects the membrane and the inner liner. In use, the release liner and inner liner are peeled away to expose the undersurfaces of the membrane and adhesive layers prior to placement of the device onto the skin or mucosa.
The present invention is an improved device for transdermal or transmucosal drug delivery in which an occlusive peel seal layer underlies the drug containing reservoir and serves to prevent release of the drug prior to use. A release liner overlays the peel seal layer and exposed portions of the adhesive overlay. In this way, the release liner need not be occlusive and thus may be chosen from a wide variety of materials that can be breathable, and can have a stretchable, elastic quality. Such devices are cost efficient and easy to manufacture.
In addition, in the devices of this invention only the central portion of the device in line with the reservoir is occlusive, leaving the portion of the device peripheral to the central portion nonocclusive or breathable.